DEVELOPMENT OF A LINING MADE FROM KARELIAN QUARTZITES
FOR CRUCIBLE INDUCTION FURNACES
A. S. Zavertkin
Translated from Novye Ogneupory,No.12pp.3–9,December 2009.
Original article submitted Jul 17, 2009.
Factors are considered that increase the service life of a lining for a crucible induction furnace. Results are
provided for laboratory studies and industrial tests of Karelian quartzites of Jotnian age of the Shokshinsk for
mation and Jatulian age of the Metchang’yarvinsk formation. The effect of impurities is quartzites on crucible
induction furnace lining wear resistance is studied. Brief characteristics of quartzites are provided. The possi
bility is established of using waste materials from quarry production of Shokshinsk quartzites for preparing
Keywords: Karelian and Swedish quartzites, lining mix, induction furnace, binding and sintering addition,
Crucible melting of cast iron, steel and non-ferrous met-
als relates to the main requirements of casting-metallurgical
technology and also exhibits economic advantages over cu-
pola melting of cast iron, and it has a cheap and rapidly re-
placeable acid lining. The economics of operating melting
furnaces and the quality of melted metal depend on the qual-
ity and service life of the lining. Specifications laid down for
lining materials relate to refractories based on quartzite.
A quartzite lining is favorably distinguished from magnesite
and alumina materials by cheapness and the fact that shrink
age is balanced by growth of quartz during allotropic trans
Domestically produced furnaces for melting cast iron,
steel and alloys based on copper mainly operate on a quartz
lining. This lining is also most widespread abroad. For exam
ple, in Germany about 90% of induction furnaces use it.
Quartzites that during quartz inversion retain adequate
strength and density are suitable for lining induction furnaces .
In crucible induction furnaces (Fig. 1) metal has a ther
mal, chemical, and erosion effect on the lining. High metal-
and slag-resistance of the lining is provided by minimum po
rosity of the sintered layer of the lining, for example of the
Swedish lining mix Radanit (Fig. 2). An acid lining of a
quartz mix has a constant volume or little growth within the
limits of 1% during service. Between the sintered part of the
lining and the inductor during crucible firing and its opera
tion a lightly-sintered (buffer) layer is created that prevents
the spread of cracks deeper into the lining towards the induc-
tor. Lining expansion gives rise to slow sintering of the
rammed walls of the crucible due to which a powder buffer
layer is retained for a long time. The safety of operating a
furnace with an acid lining is provided by the fact that the
buffer layer prevents breakthrough of molten metal to the in-
ductor. An acid lining is quite inert with respect to molten
cast iron and slag, and it exhibits the required refractoriness.
Refractories and Industrial Ceramics Vol. 50, No. 6, 2009
1083-4877/09/5006-0400 © 2009 Springer Science+Business Media, Inc.
Institute of Geology of the Karelian Scientific Center of the Rus
sian Academy of Sciences, Petrozavosk, Russia.
Fig. 1. Furnace crucible cross section: 1) bottom; 2) inductor; 3)as
bestos sheet; 4) crucible lining; 5) mold; 6) furnace collar; 7)ni
chrome wire; 8) buffer layer without H